Parameter monitoring systems can be incorporated with downhole components as fiber-optic distributed sensing systems (DSS). Examples of DSS techniques include Optical Frequency Domain Reflectometry (OFDR), which includes interrogating an optical fiber sensor with an optical signal to generate reflected signals scattered from sensing locations (e.g., fiber Bragg gratings) in the optical fiber sensor.
Some monitoring systems utilize incoherent reflectometry techniques, such as frequency modulated incoherent reflectometry and incoherent OFDR, which involve interrogating an optical fiber sensor with a modulated optical signal and combining return signals with modulated reference signals in the electric domain. Coherent light sources such as lasers are used to produce coherent optical signals, and many of the qualities of coherent sources are desirable. However, under some conditions, coherence can produce some undesirable effects in such techniques.